System for automatic transmission of messages between flight progress boards and aircraft



Juy 12, 1949. H, F, MAY

SYSTEM FOR AUTOMATIC TRANSMISSION OF MESSAGES BETWEEN FLIGHT PROGRESSBOARDS AND AIRCRAFT Flled Aug; 4, 1945 9 Sheets-Sheet 1 FeG. a'

INVENTOR. H F MAY ATTORNEY.

H. F. MAY

July 12, 1949. 2,475,848

SYSTEM FOR AUTOMATIC .TRANSMISSION OF MESSAGES BETWEEN FLIGHT PROGRESSBOARDS AND AIRCRAFT Flled Aug. 4, 1945 9 Sheets-Sheet 2 SHAFT ROTATI ROWOOIS FAST GLOGK INVENT OR.

H. F MAY FIG. 2

H. F'. MAY SYSTEM FOR AUTOMATIC TRANSMISSION OF MESSAGES July 12, 1949.

' BETWEEN FLIGHT PROGRESS BOARDS AND AIRCRAFT Filed Aug. 4, 1945 9Sheets-Sheet 5 INVENTOR. H. FI MAY ATTORNEY.

July 12 1949. v H. F. MAY 2,475,848 SYSTEM POR AUTOMATIC TRANSMISSION 0FMESSAGES BETWEEN FLIGHT PROGRESS BOARDS AND AIRCRAFT Filed Aug. 4, 19459 Sheets-Sheet 4 RADIO TRANSMITTER INVENTOR.

H. F. MAY.

ATTORNEY.

July I2, 1949. H. F. MAY v 2,475,848

SYSTEM FOR AUTOMATIC TRANSMISSION 0FV MESSAGES BETWEEN FLIGHT PROGRESSBOARDS AND AIRCRAFT Filed Aug. 4, 1945 9 Sheets-Sheet 5 PLANE MARKERRECEIVER -TO FIG. 8-

PLANE ALTIMETER UNITS FREouENcY SELEGTING Nsfwnnks RECEIVER Q llNvENTOR.

LL' H. E MAY H. F. MAY 2,475,848 SYSTEM FOR AUTOMATIC TRANSMISSION 0FMESSAGES BETWEEN FLIGHT PROGRESS BOARDS AND AIRCRAFT Filed Aug. 4, 19459 Sheets-Sheet 5 July 12,1949.

' lro FIG. 1'

Ill-III TELEPRmTER LINE INVENT OR.

H. E MAY Anm ATTORNEY.

July 12, 1949.' H, F, MAY

SYSTEM Fon AUTOMATIC TRANSMISSION 0F MESSAGES.

BETWEEN FLIGHT PROGRESS BOARDS AND AIRCRAFT Filed Aug. 4, 1945 V9Sheets-Sheet 7 VIII,

S .mi

INVENTOR.

H F MAY Y To rms.

ATTORNEY.

July l2, 1949. H. F. MAY f SYSTEM FOR AUTOMATIC TRANSMISSION OF MESSAGESv BETWEEN FLIGHT PRGRESS BOARDS AND AIRCRAFT Filed Aug. 4, 1945 9Sheets-Sheet 8 Omm\ INVENTOR. H. F M AY Y. E N m n A July 12, 1949., H.F. MAY 2,475,848

SYSTEM FOR AUTOMATIC TRANSMISSION OF MESSAGES BETWEEN FLIGHT PROGRESSBOARDS AND AIRCRAFT Filed Aug. 4, 1945 9 Sheets-Sheet 9 TELETYPEWRITER ITELETYPEWRITER TELETYPEWRITER LINE EQUIPMENT BLANK ROW 4 INCOMING DXTR.PULSING DXTR. AND

LOCATION AND STORAGE PULSING EQUIPMENT Escono sAno coMPARlson EoPT.

sEEKEn a sEouENcme Pnoemm PuLsme EQPT. I EeulPMENT cLocus DISPLAY BOARDRAmo nou. cALL REcElvEn BOARD (Gnounm RAmo TRANSMITTER A ALTHQETER v(PLANE) RAmo A I I TRANSMITTER (Rom. GALL) ruolo sELEcToR e nEcEwEnTRANSLATING Fuemognnm (PLANE) EQUIPMENT RAmo TRANSMITTER (MARKER)INVENTOR.

H. F. MAY

/u/.La-a-w ATTORNEY.

Patented Jul-y 12, 1949 ruimt-np' .2,475,848 -,SYSTEM FOR AUTOMATIC'ERANSMISSIQN lit-ESS B QAJRDS AND 10F 'MESSAGES BETWEEN ,ELI

GHTBKOG- AIRCRAFT Application vvAug-ust A4,

,18; Claims- .fx1 This relates tof communication and `,posting frSyStemsiin :which information `or .data nzegard ato a number ,of :.diierentitems, rfor example,variousrarcraft iarefdisplaye-d .on anfnounoineiboands ,byrmeanjs ,of ,indicators which are atdrnfautieany andselectinely actuatable or asettaoleintte'sponse to, incoming signais,to, display information or current changes in information, in `l`regal-dtto the-'varions aircraft or other items ."HQSQd.2151311@simientondsparticularly adapted, toi therecordationandncstingfni data atan airnort-:or ,other air trafc 'control centerrand the selettiva retransmission 'automatically to yaircraft en fronte,Hoff certain ,lot the-posted data at .pre-

determined times and visually displaying intheSelected:arriverait-atteriatatiillls retransmitted.

7'flilnefsystemdiseloseddierein,is gantextension of, alemana/deinemtafthecommunicatonfand post- .'inefsystems disclosed in- .tneMarShaH .etaL-PatGr1t No. 2,246,449, MayegaLBa-tent .Noa2-,-3v86,743, and:',Marshallietai- Batent- 0.72,'391i469.. Inonder to:eifmnlityf-tnez-present idisglosure'and' to setfgforth more -Qlearl-ythe ,improvements L represented by the a .inrentiont eertain of ,theapparatus and equipment in the aforesaid patents are:dia terammatiealirrepresentara-the drawings @fthe 'instemt tease, fthe ,ldisrlosures ,fofthe ifato-res,aid natents beine imereorateaherem by :reference yttster-r1sr ton-renewingtorfpostina @flieht plans `ss i-repontsgof,aircraft, and, other atoetheicentwl @It air- Craftthe iis-frotte amthafbulletinfor anl K ,'aiiport-or otherrontrol rsf to. entrera@fflights which-maybe ,ii titledtfloynnttmbersor\,otlierclaaracters,andthe; niiiaatorsongwlrich the; items( arerostedfare arranged interieursgorresnondinewtothe various 'timer-katerQfFiXQlssifiatens,,'andfpreferably farefarraneedwithieaehrEine-rouan,accordant@ ,with ,thefferrpectedroraestimated timeofspassae Y 'on'arnivalg'otgthe aircrattgatthe,.yarious recording.ortlma-rker ',pointsren., routegaridzatflqthe, airport.rlihancligntidataino'sted usualltifhas :to besch-angled imam mtime totime fduring-- the progress of A the flights as the result of conditionsaffectingftlfie -nroaressaof f thetairoraft, routine elflarlges,4 and@other feiraumstanees- The finiormaation posted icomprise 'numer-,ionsidata fsucn asgith'emight designation numbers, information as tothe directionmfmthe rvarious eflig-htsf ftheestmatedtimenhenftheaircraft fWill -passroyemor landgatlpertain,'marker ;p 0ints,\-a1qngtithe flieht/frontier itha @timeratfwhiehi fthe., aircraft actuallypasesbveraor zlands, at `Various markerrgpqintsntheapropnsedfaltitudegaittwhich;aclearance (ctiwfass)isitofbeor-has been issuedto cross each marker @hilight patliftlnealtitude Iat whichthe aircraft actually crosses thek various markers or:flight paths, and :other information referred tointhe aforesaidpatentslAstlnere disclosed, a recnd .Jboard: is provided having electricalsign-al storage .dev-ices, such storage relays, rotatable; indica y.tors.and settalole switch, banks, on which .control ldataotherlinformationlin regard to the Various iights may-,be .stored inrandom onder ron lthe board lAlso, there may he ,provided fa.idisplaygboard havingrotatabla indicating, .devices ,ifor displayinginformation in regardito theight's, :and saquen cing app aratuscontrolled :bythe signal storage .deviceslo'f thezgrecond board. forobtainin'g information therefrom and' automatically `,selectingandieneng'izing the' indicators ,-onzthedisf Aplay aboard .to causethemy Ito display LAin i a pre- Adeterminedserial onder the ,itemsofinforma.-

tion. storedn. the. record board.

,l In Patent2;38,6743;the;order inwhichthe items are either postedinitially. or rewritten on the .display .,zboardis determined ,floy` thesettings ,of nen/positionfstoragetdevices which are, manually :setfbyfanattendant who determines vthe desired serial. arrangement ofvthefights, to loefdisplayed `:or rewritten on i the .ldisplayi board,,whereas -lPatent12,391,469,1 thenew position storage devicesareautomaticall-yset by the incoming ,might .rsignalsto effect a;desiredserial onder of zig-hts Iwhen 'the `displayv :board isrewritten, inaccordance with,athe ;relative,nalueszaof the incoming data'concerningithe flights, which data, for example, ,may .represent4ialtitude;` or time.

VThe instant invention makes, ,the aground-to- `tfp'lane communicationslink automatic, by ,i the transmission at-the; :proper times,of.,.control;,data .suohfas routine clearance instructions zto fthepilots .sot the 4various planes .Withimag'iven control:zona and thusithe.Iautomaticommuncation endeari- -trfo`l. equipment. of the:aforesaid patents is fel- .ipan'ded lto provide ,links between planes.and igroundxstationsradio transmitters and asSQQiated;receivers,;.apparatus being ;provdedlin 'the :planes ,tonreceivecontrol data signals, ,andtranslateiand -xzisuallylmost the dataoneindicators :beor/esthe pilot. -.Each plane underzcontrol is1listed-invariousy ;se'ctions,;of;the, iflight .iprognesssboards. in ,accordancewith :the airways kfto ibe ,followed :,throughoutits flightgthealtitudes andestimatd arrival; timesloei11g.,showin,l for. :fall planesat.,f;l1 Eixes If'etheipilct ota,p'lane en froutemlllil .fl'ook` ,tinto,gtheicontrol ,room .and :see fthe; iii-eht progressrdisplay board in:the .immediateontrpll 55 -zone, ,it would. 10i-.course ,be unnecessaryl:to` send clearance instructions to him either by voice or other means.Since he cannot do this, the pres- 'ent invention takes certaininformation from the proper flight progress board and puts it into thecockpit where the pilot can see it. As an added convenience for thepilot, the system sends out at any one time only that portion of theposted information which concerns the immediate conduct of his ownflight. Controllers may plan well in advance and may post theirclearance notations and revise them when required, but each pilotreceives instructions only at the times when he must verify or alter hisconduct of the flight.

The equipment in the plane is arranged so that only instructionspreceded by the individual identiiication number of the plane willactuate the pilots clearance indicator, which indicator shows, by meansof a drum or a calibrated dial or other desired type of display, thealtitude to be flown and preferably other instructions such as Hold,Cleared to Land, etc. The system also includes means for calling thepilots attention to a change in instructions, and manual means isprovided, such as a button to be pushed by the pilot, to acknowledgeinstructions. When the pilot pushes his acknowledgment button, the

-the original clearance and, if a discrepancy is causes a repeattransmission to the Should no satisfactory acknowledgment found, plane.

be received from a plane within a given time after the originaltransmission, the iiight progress board storing device associated withthat plane is energized and a controller may then contact the pilot byvoice radio or otherwise. Various possible conditions for initiating atransl-mission to a given plane may be employed, such as (l) the postingof any control data code for a Fix for which an Over time has alreadybeen posted, (2) when the actual time approaches within a given numberof minutes of an estimate for a Fix, provided the control data code orpro- A-posed altitude at that Fix is different from the correspondingfigure for the previous Fix, (3) posting of a iiight progress report,and (4) posting of a Hold code for a Fix which will be the next onereached by the aircraft. By means of the automatic features of thesystem disclosed herein, the work load on controllers, radiocommunicators and pilots is greatly reduced-the `controllers determineand post the necessary control data, but no longer have to telephone theclearances to effect their delivery, thus gaining time for other duties;also, the communicators do not have to handle clearances and thus areenabled to give more time to other duties; the pilots receive andacknowledge clearances without having to do more than touch a button,since the record is in front of them with no necessity for copying downcodes or keeping track of flight changes to be made at some future time;and there is eliminated the time lag occasioned by the proceduresnecessary to voice communication. Moreover, the elimination of thespoken word in transmitting reports from aircraft in ight and in sendingclearance instructions to them is of considerable importance now thatextensive international trac is expected. The actual radio codestransmitted to and from planes automatically originate in and arereceived by mechanisms, and hence no problem of language need arise.Only on the flight progress boards and on the pilots clearanceindicators is there any need for human understanding, and theseexternals require only labeling in any desired language to make themunderstandable to the user. Thus, American operated planes can send outautomatic progress reports over foreign countries, and the reports willbe posted intelligibly for the airway trailc controllers of thosecountries. Similarly, a pilot of foreign nationality flying over theUnited States will see his instructions displayed in his own language.

One of the objects of the invention is a system for automaticallytransmitting flight control data such as clearance instructions or otheritems of information stored on a ight progress board at a controlcenter, to a particular plane or other aircraft at various desiredtimes, for example, at the time when the aircraft has reached a certainlocation in its flight with respect to a particular Fix or other markeralong the fiight route.

Another object of the invention is means for automatically receiving andvisually posting flight control data on indicators Within the aircraftto which the data is pertinent, whereby the pilot has his instructionsautomatically displayed, and without having to initiate a request forthe same.

A further object is a system of the character disclosed in which pilotsin aircraft receive and acknowledge clearances and other informationwithout having to perform any manual operation other than that ofinitiating the transmission of an acknowledgment which then proceedsautomatically.

Still another object is a system which eliminates the need for pilots tocopy or memorize clearances or other instructions and in whichinstructions for the immediate conduct of the flight are always postedbefore them.

Another object is to cause' a position report comprising posting signalsto be transmitted from an aircraft automatically upon the occurrence ofcertain conditions relating to its position en route.

An additional object is a system which obviates the necessity forcontrollers and radio communicators to speak clearances thereby avoidingthe possibility of misunderstanding on the part of the pilots, and alsoeliminating the possibility of human error which is present when thespoken word is relied upon for communication.

Various other objects, advantages and improvements will be apparent fromthe following detailed description of an illustrative embodiment of theinvention, taken in connection with the accompanying drawings, in which:

Figs. 1 and 2 together comprise a view, partly in diagrammatic form, ofrows of Fix, identification, time and altitude storage indicators in aflight progress record board at a control center, with cooperatingstorage relays and certain timecontrolled apparatus for initiatingtransmission of clearances and other data to particular aircraft;

Fig. 3 shows rows of Fix, identification and altitude storage indicatorsin a roll call board at the control center on which the data to beretransmitted is stored, with a distributor for pulsing the storageindicators;

Fig. 4 shows a radio transmitter and associated equipment at the controlcenter for transmitting in succession to various aircraft the controldata. posted in the roll call board of Fig. 3;

Fig. 5 shows radio receiving'and posting appathe UM contact banks, theassociated TM magnet, Fig. 1, is energized once, whereby a number ofclocks can be provided each of which may keep a different time suitablefor timing a different operation.

The time comparison takes place twice each minute, once to compare thetimes stored in the various rows of the record board with that on theminutes fast clock and once to compare the times on the record boardwith that of the 2 minutes fast clock. The cam 2I| of Fig. 2 selectseither the 5 minutes fast clock or the 2 minutes fast clock by closingits contacts A or B respectively. Cam 2I0 on the same shaft closescorresponding contacts A or B to connect in relay 5 or 2 of Fig. 2, sothat the appropriate one of these relays will operate if the indicatorsTCT, Fig. l, and TCU, Fig. 2, in the various rows of the record boardhave stored therein a time equal to that of the clock being used at thatinstant. The record board is initially posted at the time anyinformation on each flight is available, the time indicators TCT and TCUbeing set in accordance with an estimate which is made by a controllerin reviewing the flight plan.

Assume, for example, that the 2 minutes fast clock shows 19 minutes, asindicated by the bank wipers in Figs. 1 and 2, and that row I4 of therecord board has nineteen minutes posted on the TT (time tens) and TU(time units) recording indicators, as illustrated. When contacts B oncam 2| I closed (Fig. 2 shows the cam beyond the closure point), ground209 was supplied through contacts B and conductors 2 I 5, 2|6 to thecontact bank wipers of the 2 minutes fast clock. The wipers extended theground, through multiple IZI, to the contact I of all 'II indicatorcontact banks TCT (time comparison tens) and through cable 2|'| tocontact 9 of all TU indicator contact banks TCU (time comparison units)in the record board. In row I4 the time tens ground was extended throughthe bank TCT of the TT recording unit and conductor |22, through thewinding of the tens comparison relay TC and conductor |23 and innerarmature `and break contact on a gang relay GA|4 to battery, operatingrelay TC. The record board gang relay GA-I4, which connects the recordboard indicators of that row to pulsing circuits so that an incomingmessage can be stored on the indicators, is shown only in partialdetail, with but a few of its armatures and connections ||8, since theseare fully disclosed in the aforesaid Patents 2,386,743 and 2,391,469 anda detailed disclosure herein is not necessary to an understanding of theinstant invention. The time units ground was extended through the bankTCU of the TU indicator recording unit, Fig. 2, the armature and makecontact 220 of operated relay TC, contact B of cam 2IG, and Winding ofrelay 2 to grounded battery. Relay 2 operates and locks up through itslower inner make contact and armature 222, and break contact andarmature 223 of relay RLS- I4 (which previously had been deenergized bythe opening of the C contacts of cam 2I0) to ground on operated armature224 and make contact of the relay 2. Whenever a relay 2 or 5 is operatedin the record board of Figs. l and 2, the information on that flight istransferred to the roll call board, Fig. 3, which carries data on allflights to be communicated with.

Transfer to the roll call board, Figs. 3 and 4, is effected when therotary selector switch RF, Fig. 2, arrives at the position correspondingto the row in which either relay 2 or relay 5 has been previouslyoperated by means of a time comparison. The selector switch RFcontinually hunts over the rows of the record board whenever any relay 2or 5 is operated, as explained in detail under the following headingPosting the roll call board.

Posting the roll call board The roll call board is posted by adistributor DR-I in conjunction with a self-interrupting rotary steppingswitch RF, Fig. 2, which finds the proper row in the record board in thefollowing manner. The operation of relay 2, at its armature 224, removedground from terminal I4 of multiple 228 leading to the contact bank ofrotary row nder switch RF so that the switch would stop at thisterminal. Operated relay 2, at its armature 22E and make contact, alsoplaced battery on a multiple wire 230 and connected through the lowresistance Winding of slow-release relay SR-I to the coil of thestepping switch RF'. Since the switch is arranged for buzzing operationit moves around to the first ungrounded terminal on its bank H, in thiscase terminal I4. The SR-I relay, which remained operated during thebuzzing operation now releases, provided its right-hand winding is notenergized which would Ibe the case if the roll call board blank rowlocating switch BRL, Fig. 3, was hunting. When SR-I, Fig. 2, releases itmomentarily energizes start magnet SMP, Fig. 3, releasing the .brush blof distributor DR-I, through a circuit comprising grounded armature 239and break contact of SR-|, Fig. 2, armature 23| and make contact of theoperated slowrelease relay B (which was operated when relay SR-Ioperated) and conductor 232 to SMP. T-he release of SR-I applied ground,from grounded armature 3| 0 and break contact of release relay RLS ofFig. 3, conductor 3II, armature 234 and break contact of relay SR-I,Fig. 2, through bank M of switch RF and conductor I4 in` multiple 236(since the wiper M has come to rest on row I4), and the right-handwinding of relay RLS-I4, which relay operates and locks to cam contact Cof cam 2|Il. A rectifier 242 eliminates a feed-back current path fromgrounded armature 224 of relay 2 upon operation of the latter relaywhich otherwise would cause premature operation of relay RLS-I4, whereasrelay RLS-I4 operates only when the wiper of switch bank M reachesterminal I4 of its bank and applies ground potential to conductor I4 incable 236. RLS-I4 and its armature 223 and make contact, operates relayGS-I4 which, through its armature and grounded make contacts grounds thewipers of the recording indicator units in row I4 and transfers thesettings of these indicators to storage relays FS, ITS, IUS, Fig. 1, andATS, AUS, Fig. 2.

'Ihe brush bi of distributor DR-I of Fig. 3, when it leaves the segmentI, releases relay RR which, through its grounded armature 3| 2 and breakContact, grounds the left-hand wiper of a self-interrupting steppingswitch BRL which can only rest on a blank row, in this case assumed tobe row U4 of .the roll call lboard. This ground, through .conductor 4 ofmultiple 3|4, operates relay RGA of row 04 which, through its uppergroup of armatures and make contacts I to 6, connects the recordingindicator units F, IT, IU, AT and AU of row 04 of the roll call boardthrough multiple |29 to the indicator pulsing equipment which includesrelays P-I, P-2, Pf4 and P-l.

RF. Relay 2 releases, vbut relay RLS-I4 remains locked to contact C ofcam ZID. Relay 2 at its armature 224, releases relay GS-I4. RLS-I4 isreleased only when cam C opens, thereby to `prevent multiple transfer tothe roll call board of the same flight until the time changes at the endof each minute.

Transmission from roll call board to aircraft The flight in question hasnow been transferred and posted on the roll call board, and the data ineach row of the storage indicators of the roll call board is transmittedautomatically in succession via radio at the proper times to all planestuned to the range transmitter. Preferably, although not necessarily,audio frequencies in permutation code arrangement are employed fortransmission, whereby the plane identification and data may betransmitted without interrupting the usual radio range signals. By theprovision of an address reading circuit in the plane, only the planecalled receives the message intended for it. In the embodimentillustrated herein, two types of transmission are made to the plane, oneto transmit a clearance and the other to request an acknowledgment or areport. The plane makes no response to the transmission of a clearance,but in the next roll .call cycle a request for an acknowledgment istransmitted This gives the pilot time to acknowledge the receipt of themessage by pushing an Acknowledge -button in the plane. Theacknowledgment consists of a repetition of the original message, and inaddition a position report is also transmitted if the plane haspreviously passed a particular Fix or marker. When a report isrequested, the same process takes place.

The distributor DR2 of Fig. 4 controls the transmission to the aircraftof the information stored in any row of the roll call `board concerningsaid aircraft. Each time the distributor sends a message it advances therotary switch RC to .the next row in the roll call board desiring tosend a message to an aircraft. Whether or not any row in the roll callboard desires to send a message is determined by the setting of thestorage indicator S of Fig. 4. The indicator S also keeps track of thenumber of times a given message is sent so that the message stored in arow of the roll call board is sent only a predetermined number of timesbefore giving an alarm either that an acknowledgment or a repont, or thecase may be, has not been received from the particular aircraft.

The choice of what message is to be sent to the plane is determined bythe setting of the S indicator, Fig. 4, which in turn was controlled,over conductor 6 in multiple I 29 by the S-Z and S-5 storage relays,Fig. 2, when the roll call board was posted. Preferably, and asdisclosed, a report is requested three times and an acknowledgment oncebefore bringing in an alarm.

When the roll call board was posted, armature 334 and make contact ofrelay RGA, Fig. 3, of row 04 caused the operation of relay BR in row 04which locked, over conductor 335, to relay RL, Fig. 4, of row 04. WhenRGA in row n4 released, after the information was stored in row 04, batntery was applied through its armature 334 and armature 336 and makecontact of relay BR to a multiple lead I in multiple 331, therebyenergizing RC switch magnet, Fig. 4. The release of relay RGA and theoperation of relay BR re.- moved ground from conductor 338, conductor 4in multiple 420, and terminal 04 of switch bank H of rotary switch RC,Fig. 4, so that the switch will stop at this terminal. During thehunting, relay SR-3 has been operated and this, at its grounded armature422, held relay B-I operated. When SR-3 releases, its armature 424applies ground to the M bank of switch RC and thence over conductor 4 inmultiple 440 to operate relay RGS of row 04 in the example assumed.Release of SR-S also energizes, through its armature 422 and breakcontact, and make contact and armature 423 of relay B-I, the startmagnet SMT of distributor DRf-2. The operation of RGS connects, throughmultiple 331, the Wipers of the recording indicator units IT, IU, AT andAU of Fig. 3 to the segments of the ring of the distributor so that thebrush b2 in passing over these segments will ground in succession thewipers of the above named recording indicator units.

Operation of distributor DR-Z As the distributor brush b2 groundedsegment l, relay CC, Fig. 4, operates and at its armatures and makecontacts connects audio frequency oscillators fl, f6, (represented bynumbered circles) over conductor 425 to the input of the radiotransmitter at the ground station. Any suitable audio frequencies may beemployed, and the combinations of these audio frequencies correspond topermutation codes representing the numerals and guard characterscomprising the message to =be sent to the plane. Thus, f I and f5 is thecondition code for conditioning all plane receivers to begin reception,as will be noted from the `chart in Fig. 9, i. e., it indicates thebeginning of an address.

When the brush b2 of distributor DR-2 grounds segment 2, this ground isextended over conductor 2 of cable 331, through bank terminal 0 ofrecording unit IT of the roll call board, Fig. 3, and conductor 0 ofmultiple 342, to operate relay I-, Fig. 4, which connects the sources offrequencies fl and f2 (represented by numbered circles) to the radiotransmitter. On segment 3 of the distributor DR-2, a similartransmission under control of recording unit IU of row 04 operates relay1 8, Fig. 4, and sends the code for 8 (f3 and f5) through the radiotransmitter.

When the brush reaches segment 4 of the distributor DR-Z, relay LCoperates, and through its armature and make contacts, transmits the lockcode f2, f6. From segment 5 the distributor sends a -code controlled bythe recording unit S, Fig. 4, of row 04, which unit holds the C relayoperated so long as relay RGS of row 04 is operated. Through thearmature and contact of the operated C relay, relay CR is operated, andthis transmits the code f6 corresponding to the transmission ofclearance. Ground from segment 6 of the distributor DR-2 is applied toconductor 8 of cable 331, and through the left-hand make contact andarmature of operated relay C-I, conductor 4 in cable 331, and wiper andcontact 0 of the bank of recording unit AT, Fig. 3, and thence throughconductor 0 in cable 344, to operate relay A-U of Fig. 4, thereby tosend out the code for D under control of relay C-I and recording unitAT. The code used in this case is f3, f4 and f5. The duration of thischaracter transmission and the succeeding one comprising frequencies jl,f2 and f3 from segment 1 of the distributor DR-2 is longer because thesecharacters are used to set the indicator units in the plane, and theyrequire a longer pulse to permit the plane indi- 113" cators to reachV afinalsettingfinaccordance with the datadisplayed on therecording unitsAT. andL AU of Fig. 3.

From segment 8 of distributor DRA-2; ground isY applied through breakcontacts 421' and lf2-8v of relays RB and RLC, and conductor 5 of cable-331, to energize the coil of recording unit'S, Fig. 4, in row 0i oi theroll call board; Thelsame ground, through another break contact d ilfoRBC, also' energizes, throughconductor 431, the magnet of rotary switchRC. When the 'distrib--l utor brushileaves segment-8,the S recordingunitadvances to the Acknowledge position; The' wipersI of rotary7 switchRC"y leave positionv 04 .and the switch buzzes to the next occupiedfrowin the roll call board `where another message is to beV transmit-ted t0adiiierentplane or planes enroute;

Operation' of plane" re'ceicei'` The operation of lthe planereceiver,Fig.4 5, in response to the message justtransinitted is as follows. Uponreceiving thev condition code .frequencies (fi and f), frequencyselecting:y net"-v works fl and f5 llocated in the audio output'oyftheplane radio receiver passed current, through rectiersy 5m and 57i I,tooperate the receivingrelays PR'-I and- PR-G, thel operating pathofPR--B including 'conductor 5I 2.Y The operation of relay PR---i` causesoperation of relay A by connecting ground thrmgih the make contact andarmature 5M oi PR-G, bank terminal-strap* 515, bank terminal 0 andwipe-r of` .bankr D. Groundufrom the wiper of bank A of therotaryswitch'SEL is applied through the armature and make conta-ct 525 ofrelay PRf-Lconductor 522'. bank C', and innerrnake contacts-A 5244 ofrelayv A, and operates the SR2-4 relay and rotary selector lmagnet SELinseries. lAt the end of this pulse the selector switches SEL ingailvplanes tuned to' the incoming radiol signals advance their wipers onestep .from contacts to i.- Relay SRithereafter remainsoperated so longas the switch receives successive impulses,V but will release'ii onepulse is skipped:

Following the condition code fl and` f6, the iirst digit of theidentification is transmitted; this is 0, codefi, f2.U Ground fromvthe'fwipery of bank A of switch S-EL,which is now in positionj l,through. bank strap SI5 and'make contacts 5H of the operated SR-4 relayis supplied tofA the lower outer set' of rnake contacts-dfrelays PR|^-vto Pit-5. Relay PRI- 12,v which is now operated by code f2, extendsthis" ground through confductor 5|? and' bank D of switch SEL to operaterelay A. Relay PRi extends this ground through conductor 522-and bank C,andthe armature 524 and rnakeacontact of relay A-,ft-o step the rotaryswitch SEL. The terminalsV l'v and-,2 on' switch banks C and D areconnected tothe PR4 relays corresponding to the particular planesidentiiication, all other planes being connected' differently. In asimilar manner'the receptionv of the digit 8, which is the second digitof the identification, will againstep the switch SEL' in the planedesignated by the identification number B8, but will fail to do so inother planes. When this happens in the other Iplanes their re' laysSRf-d release beca-use they do not receive' a pulse from the relayscorresponding to the identiiication code which is beingv received', andremove ground from their relays Pfc-'1 to PRL-L5, and this connectsground through thej in-N terrupter contact to the SELv stepping magnet.-Th'e'switc'hes in a'lfll planes except 08v return' to P45riormakbyselfinterruptionsi and. since the -conI-` dition code isno-t?sentI again', they do not restart.-

In' plane: 08'- the i switchI SEL f continuesE to`-- a'd trance',Lreceiving the identification and lock codes Having? passed" thesleotioiif phasel oi the' message at' contact' 4f on' switchba'nk E.y the'jwinding di' relayV PRA-"Gf is connected by meansV df' conductor548'andirctier 519, as avuniversa'l' relay torespondfto any frequencysignal. The

" armature 521i.-i of relay A alsoy isA connected to tb" operate'frelayBT.' Thislr'elay starts-'theplane transmitter? tb transmit either anacknowledg meritiora report: IF instead? off code 3; codeis sentirmerotary switch-SEL-mereiysteps beyond' l this point.

Wheni the'sele'cto s-"witchA SEL is' in' position 5, the electrmag-net(altitude tens) of the" rer cording indicator unitcomprisingy dialy 544iin the planet is*y connectedbyvr conductor 2l in' cable 51H1 and Contactifl'bank' Bioi switch SEL;l to battery". In this position the'cdef' fortlierst character of the data`| isfreceivedi and posted.l This char--vacter inathe-presentzexample is tlg. andA the code is f3, ffii )F52yWhen3 this code isreceived the -grourd'present'4 oir conductor "522y`is' connected' from relays PR-`'3,.PPR=4 and'PRL5to all bank` terminals:of-the" recording` indicator unit except those terminals in the 0positiom These'groundsf completes. Seli-interrupting`l circuit through'the rectiiiers 542i- 545/ andy conductors iv and 3 ofI multiple' 5215,and' the ATR`y indicator magnet to buzzvthe indicator andI its' dial544' to itsl il display position; The. codev pulse isv applied forasu'iiiciently longtime to enable theindicator tobuzz tot any position.AAt'the'conclusion of the pulse the selector switch-SEL steps to position6', and-v the code. for liaositioni-ngl the recording.l indicatorv unit'(altitude units) and' its dial 545- is'A applied; When' the" pulseceases; the selector switcisEh-steps to' its Ill position'. If no dataii station is. again reached; a transmission of the planesidentiicaition: followed by the transmit code will; be sent by thegroundv transmitter. No; datal will beatransmitted', however, since theC irelay, Eig. 4o i-sI-unoperated and the conductors:

i @and S'frorn segments 6 and 'l ofthe distributor.

DR-2 are open. The reception of the transmit signal by plane 08 willoperate its BT relay, Fig. 5, which in turn will step rotary switch TRSoff normal. A slow speed self-interrupting circuit will be establishedthrough conductor 549 and bank D of switch TRS to continue stepping theswitch through its complete cycle. Each time that relay BT operates, itsgrounded armature 548 and make contact will energize the TRS magnet ofthe switch and also will energize an oscillator to generate allfrequencies fl-f used for transmitting the acknowledgment, whichfrequencies are generated by the harmonic generator diagrammaticallyshown. The required frequencies for each character of the transmissionare selected by the position of the TRS switch and the recordingindicator units ATR and AUR. The preliminary condition code is sent bybanks A and B in position of the TRS switch. Following this, the switchsteps to position l and sends the first digit 0 of the planeidentification through the same banks A and B. In a similar manner thenext digit of the identification (position 2) and the locking code(position 3) are sent. In positions 4 and 5 of the TRS switch thesettings of the recording indicator units ATR and AUR are transmitted.If the PR relay had also been operated, the data on the recording planealtimeter would also have been sent in a similar manner.

The PR relay is operated, however, only if the plane has passed over aFix marker prior to the roll call, since it is operated from the MFrelay which in turn is operated by the audio frequency used to modulatethe Iix marker. The Fix signal is transmitted, in known manner, by ahighly directive Fix marker transmitter at the Fix ground station, andreceived by the plane marker receiver. If relay PR is operated,terminals 5 and 1 on bank C of the TRS switch are connected through thearmature 548 and make contact of PR and conductor 550 to the plane radiotransmitter, Fig. 8.

When the radio signals from the plane are received by the radioreceiver, Fig. 7, at the ground receiver station, the reception of thecondition code steps rotary selector switch RR oi normal and successivecharacters received advance the switch through its cycle. The groundreceiver selector operates in a manner similar to the plane receivingselector, but instead of advancing only when a particular identiricationcode is received, the switch RR responds to any identication code. Theonly requirement to keep the switch stepping is the reception of thecondition and lock codes when the switch is in positions 0 and 3respectively. As the characters of the identification and the messageare received they are stored in relay groups SIT [-5, SIU I-5, SAT l5and SAU I-5, Fig. 6. If a report had also been transmitted it would havebeen stored in groups SHT I-5 and SHU l-5, Fig. '1. Each relay group isconnected in succession to relays RR-l to RRf-5, Fig. '1, throughassociated cut-in relays ITR, IUT, ATR, HUR, HTR and HUR which areoperated successively over conductors I to 6 in cable 620 by thegrounded wiper and contacts I-B of bank A of switch RR.

It will be recalled that transmission started when the distributor DR-2,Fig. 2, reached segment 5. The receipt of the condition code from theplane operates the SR--2 relay, Fig. 1, associated with selector switchRR. Ground from armature 139 of the SR-2 is applied to conductor 1 incable 140 and operates relay RB, Fig.

4, opening, at armature 431 of the latter relay, the circuit fromsegment 8 of the distributor DR-Z. Consequently, if the plane respondsto the request to transmit, the release pulse from segment 8 of thedistributor is interrupted and switch RC continues to hold row 04 in theroll call board.

As each received character is set up in the storage relay groups SIT toSHU of Figs. 6 and 7, ground is applied to one of the conductors 0 to 9in multiples 622 to 628 leading from the groups corresponding to thecharacters received. The leads from the storage group contacts aremultipled to the banks of the corresponding recording units in the rollcall board. Thus, group SIT [-5 is multipled to the banks of the ITrecording units in all rows of the roll call board. Assuming that thefirst message received by the plane had been CC, U, 8, LC, Trs, theplane would have sent back CC, U, 8, LC, 0, 9 if the PR relay, Fig. 5,had been unoperated. The receipt of this message by the ground receiverwould have resulted in energizing the 0 conductor in multiple 622 of theSIT |-5 group, conductor 8 in multiple 624 of the SIU |-5 group, the Dconductor in multiple 625 of the SAT |-5 group and conductor 9 inmultiple 628 of the SAU |-5 group. The lead 0 from the SIT |-5 group ndsa path through the B bank of the IT recording unit in row 04, Fig. 3,and operates relay ITC in that row. Similarly, if an exact duplicationof the first message is received from the plane, relays IUC, ATC and AUCwill be operated in row 04. A series comparison circuit will beestablished through the armatures and make contacts of relays ITC andIUC from ground 350 at the TT storage unit through the RGS relaycontacts, conductor 352, armature and make contact of relay AK,conductor 353, armatures and make contacts of relays ATC and AUC, andconductor 35| to the winding of the RL relay, Fig. 4, of row 04. The AKrelay armature and make contact is in this circuit because the AK relayhas been operated from bank B of recording unit S, Fig. 4, which hadadvanced to terminal l after transmitting the first message. When relayRL operates, it operates relay RLC through conductor 1 in cable 331.This occurs when rotary switch RR, Fig. '1, had reached position 5 ifthe received message agrees with the information in the roll call board.

When rotary switch RR passes position 8, ground from relay REP issupplied through bank A, conductor 5 in cable 140, armature 430 and makecontact of RLC, Fig. 4, conductor 2 in cable 140, break contact of relayREP, Fig. 7, conductor 3 in cable 140, conductor 43|, Fig. 4, conductorI of cable 331, armature 336 and make contact of relay BR, Fig. 3, andbreak contact and armature 334 of relay RGA to battery, to advance therotary switch RC, Fig. 4, ofi'` row 04. When the switch RR, Fig. '7,reaches position 0 the relay BRS, is operated, releasing relay groupsSIT l-5, etc., of Fig. 6, which are locked up over conductor 635, andrelay RLC, Fig. 4, which was locked up over conductor 436.

If agreement had not occurred between the received message and the datain the roll call board, relay RLC would not have operated. When switchRR of Fig. '7 reached position 8, ground would have been sent throughthe armature 430 and break contact of RLC to advance switch RC and the Srecording unit to position 2. In this position an alarm lamp ALM wouldhave been lit, and the terminal 04 on bank H of rotary switch RC wouldhave been made busy from batteryvonconductorrd .ofymultiple 420, so theswitch RC would not again stop in this. position. An attendant.responding to.the. alarm..wo uld contact ,the plane Vby voice., andhaving cleared up the .situation-would release relay BR, Fig..3, by man-,ually operating relay RL, Fig. 4. -This would make row ,04 availablefor a new roll calll posting. If a; report had been received in addition`to 4the acknowledgment, the report data would have been .taken-from thecontacts .of the plane altimyeter, Fig. 5,. which is recording/altitude2l! in this vexample. The figure y2l) would` havebeenstored in therelays of groups SHT and SI-IU, Fig. 7. The `presence of. .locked uprelays in. SHUwould yoperate thelow resistance series relay. REPconnected to. the .locking lead.630. v',Ihis relay, at its armature 148and break Contact, opens the circuit 4.of relay BRS, Fig. 4, and-.whenswitch` RR, Fig. 7, passes ,terminal .8 .a circuit. is .established toenergize .the start magnet ASMR of distributor ,conductor I,i ncable.63,2, armatureldand .make rcontactvof relay REP, .conductorl incable 143, and -make contact ofarmature 430 ofrelay RLC, conductor?)incable 140, andterminal .8 .of ,bank

A ,of switch RR. yIt RLC has. not been operated recording unit Sisadvanced to the alarm .posi- ,tion 'and switch, RC is advanced.

YDistributor DR--3 'When distributor A2DR-+3 ofFig. 6 goes through itscycle,` the data stored in relay groups SIT, SIU, `SJHT and SHU 'aretransmitted. over a tclcprinter ...circuit to thcinooming lineyequipment shown .in the.aforesaid-patents. The method of .postingthejdata is 'the same as that employed for posting anyothcr incomingdata- Such messages are in thej form Ident tens, Ident units, Fix,Range, jData tens andData units. TheI Identand VData are taken from 'theabove `mentioned storage relay groups. The* vFix is taken from the'Frecording unit of the roll call board, Fig.' 3.

Local rings A and `B of'distributorDR-tonerate 'through conductors'Z to6 .in cable'632, to cut in the relays IT, FgHT andi-IU of Fig. 7 insuccession. The range to 'be posted is .always the Hiactual altitude)range so v.this lcodev I, 2, 5)` is permanently wired on thelinexcircuit ring D. vThe operation of a cut-in relay, asshown by relayF in'FigJ'Uconnects the ten leads'pfrom the associated vstorage ygroupto a group of translating relaysR-U to R-9, the armature 150 andmake`contacts of -which apply the corresponding five nuit teleprinter codeto the distributorringD.

The grounds applied to the segmented ring, D l

appliedlthrough segment 1 of ring'B to the BRS vrelay, Fig.4. This relayreleases the locked-up l -stor agejgroupsfof Figs. -6 and 7 and also therelay -REP. 'iREP-'deenergizes andsat its armature 1.48 yand breaklcontact, restores the circuit from groundonfbank A' of switch RR to thewindingY of .relayilBRS which remains operated. The `Operation of BRSalso releases RLC and closes lthe lbuzzing-"circuit of -switch RC. A1fany other rows .in thefroll callboard are awaiting transmission,f-switch RCpr-'oceeds-qto these rows and the roll call cycle continues.

Whenever a row ofthe roll call board is in inse, or=has datastored'therein awaitingv transmisvvsiorrfits vrelay IBR.' Fig.' 3,- islocked up, andthe .20 llplltjt,Fig-.8, .provided relay RLCzisoperatedover rowfmderswitch BRL cannot select the busy row .becauseground from the outer left-hand armatureand make contact of BRisappliedto a conductonsuch as conductor.4, in multiple 308, and

lcausesa ground potential to be maintained on the corresponding terminalof the BRL switch bank, thereby .causing theswitch BRL to buzz pastsuchrow Iand -select thefnext available idle row.

.Various .modifications of. the circuit .arrangements Yand `apparatusshown, and various equivalents. or .substitutes for the, devicesillustrated, will occur to those versed in the fart Without departingfromthe spirit andscope of the present invention. kThe diselosure,therefore,.is for .the purpose of illustrating the principles -ofz the`.invention ywhich is not 'to be regardedas .limitedexvcept .asindicated by the scope of the .appended claims.

What isclaimcd is r 1. A4 system .for .posting .and retransmittinginfomation regarding the movements ofv aircraft,

,oomprisi-ngan assembly yof flight progresspos'ting apparatus. .havingsignal storage elements respcctivclyassignable. to .different flightsfor-storf i'ng information .in regardthereto, saidl informationcomprising flight `identiiication indicia and vcontrol data, including`predicted times. when .in- ,dividual aircraft should reach 4a certaingeographical locationalong their-respective iiight routes,

andmeans including .a signal. transmitter for automatically transmittingsuccessivelyto therespective aircraft. at vparticular.times-.asdetermined l by ,said yposted .predicted times, Vsignals coniprisina.`their ,individual flight identification indiciaand Certain .of thecontrol data v.nostedon saiclight posting apparatus.

,2. .A System. iorposting and retransmitting information,regardingthemovements of aircraft,

.comprisingan assembly. of flight Yprogress ,posting yapparatus.embodying aplu ra1ity .of groups vof signal 'storage ,devicesassignableto differcntones of Said aircraft, .and .actuatable t0vdiiferentsettings for storingthe .aircraft .identification ,indicia.and. @control Ydata in regard thereto, -and meansyfor automaticallyinitiating transmission at l,predetermined timosto said .aircraft Aofflight identication ,signals and .posting SignalsV ycomprisms` certain.,of ...said ,data Storedv .on the .flight progress posting apparatus,said identification signals .being .of such charactenas to lock Ont thereception of their accompanying posting signals lbythose of saidaircraft which have ldifferent identification signals.

`3- 'A ,System for posting information regarding 'the movements ofaircraft, comprising an Vassembly of; Vflight progressApostingjapparatus embodying a pluralityofgroups 'of signal storagedevices,

assignableto .different ones of said aircraft, and

.the'movements of aircraft, comprising an assembly of fliahtprogressposting apparatusembodying a pluralityl of groups of signalstoragedevices,

.assignableto diierent ones of said aircraft, and

actuatable tn diierent settingsfor storingthe iairoraftiidenticationindi-cia .and control data in regard thereto, means controlled by aselected group of said storage devices for automatically initiatingtransmission at predetermined times to a. corresponding aircraft of itsfiight identification signals and posting signals comprising certain ofsaid data stored on the flight progress posting apparatus, said aircrafthaving receiving apparatus selectively responsive to its flightidentification signals and an indicator device responsive to the postingsignals which accompany its flight identification signals for visuallydisplaying the received data.

5. A system for posting information regarding the movements of aircraft,comprising an assembly of flight progress posting apparatus embodying aplurality of groups of signal storage devices, assignable to differentones of said aircraft, and actuatable to different settings for storingcontrol data in regard thereto, means for automatically transmitting tosaid aircraft posting signals comprising certain of said data stored onthe flight progress posting apparatus, said aircraft having receivingapparatus including an indicator device responsive to the postingsignals for visually displaying the received data, and means in saidaircraft for initiating an acknowledgment of the received messagecomprising means controlled by the settings of the aircraft indicatordevice for transmitting the data displayed thereon.

6. A system for posting information regarding the movements of aircraft,comprising an assembly of flight progress posting apparatus embodying aplurality of groups of signal storage devices, assignable to differentones of said aircraft, and actuatable to different settings for storingthe aircraft identification indicia and control data in regard thereto,means for automatically transmitting to said aircraft flightidentification signals and posting signals comprising certain of saiddata stored on the flight progress posting apparatus, said aircrafthaving receiving apparatus selectively responsive to the flightidentification signals and an indicator device responsive to the postingsignals for storing and visually displaying the received data, and meansin said aircraft for transmitting an acknowledgment of the receivedmessage comprising means for transmitting the flight identificationsignals and means controlled by the settings of the aircraft indicatordevice for transmitting the data displayed thereon.

'7. A system for posting information regarding the movements ofaircraft, comprising an assembly of flight progress posting apparatusembodying a plurality of groups of signal storage devices, assignable todifferent ones of said aircraft, and actuatable to different settingsfor storing the aircraft identification indicia and control data inregard thereto, means for automatically transmitting to said aircraftflight identification signals and posting signals comprising certain ofsaid data stored on the flight progress posting apparatus, said aircrafthaving receiving apparatus selectively responsive to the fiightidentication signals and an indicator device responsive to the postingsignals for storing and visually displaying the received data, means insaid aircraft for transmitting an acknowledgment of the received messagecomprising means for transmitting the flight identification signals andmeans controlled by the settings of the aircraft posting indicatordevice for transmitting the data displayed thereon, and means associatedwith said flight progress posting apparatus for receiving andautomatically comparing the acknowledg- 20 ment from the aircraft withthe message transmitted thereto.

8. A system for posting information regarding the movements of aircraft,comprising an assembly fiight progress posting apparatus embodying aplurality of groups of signal storage devices, assignable to differentones of said aircraft, and actuatable to different settings for storingthe aircraft identification indicia and control data in regard thereto,means for automatically transmitting to said aircraft flightidentification signals and posting signals comprising certain of saiddata stored on the flight progress posting apparatus, said aircrafthaving receiving apparatus selectively responsive to the flightidentication signals and an indicator device responsive to the postingsignals for storing and visually displaying the received data, means insaid aircraft for transmitting an acknowledgment of the received messagecomprising means for transmitting the flight identification signals andmeans controlled by the settings of the aircraft posting indicatordevice for transmitting the data displayed thereon, means associatedwith said flight progress posting apparatus for receiving andautomatically comparing the acknowledgment from the aircraft with themessage transmitted thereto, and means controlled by said comparisonmeans for automatically retransmtting said message to the aircraft inthe event of disagreement between the message and said acknowledgment.

9. A system for posting and retransmtting infomation regarding themovements of a plurality of aircraft, comprising an assembly of fiightprogress posting apparatus embodying a plurality of groups of signalstorage devices, assignable to different ones of said aircraft, andactuatable to different settings for storing the aircraft identificationindicia and control data in regard thereto, and means controlled byrespectively different groups of said storage devices for automaticallyinitiating transmission successively at predetermined times to each ofsaid aircraft of their respective flight identifications signals andcurrently stored posting signals comprising certain of said datapertinent thereto, said identification signals being effective whenreceived by the aircraft to which they do not correspond for locking outthe reception of their accompanying posting signals by such aircraft.

10. A system for posting and retransmtting information regarding themovements of aircraft, comprising an assembly of iiight progress postingapparatus embodying a plurality of groups of signal storage devices,assignable to different ones of said aircraft and different Fixdesignations, and actuatable to different settings for storing theaircraft identification indicia, Fix designation and data in regardthereto, and means for automatically initiating transmission to aparticular aircraft at the time when it should have reached a certainlocation in its flight with respect to a particular Fix along the flightroute, of its flight identification signals and posting signalscomprising certain of said data pertinent thereto and currently storedon the fiight progress posting apparatus.

11. A system for posting and retransmtting information regarding themovements of aircraft, comprising an assembly of iiight progress postingapparatus having signal storage devices respectively assignable todifferent fiights for storing aircraft identification indicia andcontrol data relative thereto, said control data including predictedtimes when individual aircraft should musees reach acertainrgeegraphical.location along their respective flight routes,means including a chronological memberfifor selectinge said= rstoragedevices sequentially according to @the l`predicted timesstored;thereingtansignal.transmitter, and means gperative under controlof said chronologicar member for causinges'aid transmitter 'to transmitmessages including -sai`didentification irifcli'cia-'fandf'certaineofrsaid *cont-rol data fas' derived ifromttheselected storag'eevices "1;72.`Aisystem `forposting and fretransmtting'informationJ regarding' the"movements of-` aircraft, comprlsingan assembly-of*flight-progressposting apparatus#embodying-a-pluralityof groups iof signal f storageMdevices, Aassignable to 4idifferent ones ofsaid-aircraftfandeactuitable to'fdiifer'ent settings for storing controldata in regard thereto, and means for automatically initiatingtransmission at predetermined times to said aircraft of posting signalscomprising certain of the data stored on the flight progress postingapparatus, said means including a chronological recording device andassociated circuit means for comparing the time data currently stored insaid signal storage devices with the time recorded by said chronologicaldevice.

13. A system for posting and retransmitting information regarding themovements of aircraft, comprising an assembly of flight progress postingapparatus embodying a plurality of groups of signal storage devices,assignable to different ones of said aircraft, and actuatable todifferent settings for storing control data in regard thereto, and meansfor automatically initiating transmission at predetermined times to saidaircraft of posting signals comprising certain of the data stored on theflight progress posting apparatus, a plurality of chronological devicesrespectively recording different times, associated circuit means forcomparing the time data currently stored in said signal storage deviceswith the different times recorded by said chronological devices, andmeans controlled by said chronological devices for determining which ofsaid data shall be transmitted.

14. A system for posting and retransmitting information regarding themovements of aircraft, comprising an assembly of flight progress postingapparatus embodying a plurality of groups of signal storage devices,assignable to different ones of said aircraft, and actuatable todifferent settings for storing control data in regard thereto, saidcontrol data including the predicted times when individual aircraftshould reach a certain geographical location along their respectiveiiight routes, an assembly of roll call apparatus embodying a pluralityof groups of signal storage devices actuatable to different settings forstoring different control data respectively in regard to a plurality ofsaid aircraft, means controlled by said night progress posting apparatusfor automatically posting on said roll call apparatus in the sequence ofsaid predicted times certain of the data stored on the flight progressposting apparatus, and means for automatically transmitting selectivelyto said aircraft their respective posting signals comprising the datastored on the roll call apparatus.

15. A system for posting and retransmitting information regarding themovements of aircraft, comprising an assembly of flight progress postingapparatus embodying a plurality of groups of signal storage devices,assignable to different ones of said aircraft, and actuatable todifferent settings for storing control data in regard there- L2to;said.control-:dataincluding thepredicteditimes whenaindividualaircraft `should reach-:avcertain geographicalilocation .alongther'respective iight routes, l ian iassembly of roll call apparatus 1embodyinga plurality-.fofigroupsfiofsignal storage devices:actuatablento different-.settings for storing different controlfdata:respectively iin regard tecasplurality fofc said i aircraft, tmeans,controlled byzsaidiflightprogress posting apparatus for automatically'.posting on` said; roll callfv apparatus lin the sequence-ofsaid-:predicted :times certain of thetdata storedfon the flight:progress iposting apparatus pertinent ,to` :selected ones -of theaircraft, and @means for: automatically. transmitting successivelyandfrselectivelyV` to saidaircraft their respectivemosting signalscomprising the 'data stored on the rollcall-iapparatus.

16. nAf systemforaposting information regarding the movements ofaircraft, comprising an assembly of night progress posting apparatusembodying a plurality of groups of signal storage devices, assignable todifferent ones of said aircraft, and actuatable to different settingsfor storing the aircraft identification indicia and control data inregard thereto, means for automatically transmitting to a selected oneof said aircraft its individual night identification signals and signalscomprising a request for a report from the aircraft, said aircrafthaving receiving apparatus selectively responsive only to its individualflight identification signals and a settable device for storingelectrical signal conditions comprising a report, means in said aircraftfor transmitting said report comprising means for transmitting itsindividual iiight identification signals and means controlled by thesettings of the aircraft signal storage device for transmitting signalscomprising the report data stored therein.

1'7. A system for posting information regarding the movement ofaircraft, comprising an assembly of flight progress posting apparatusembodying a plurality of groups of signal storage devices, assignable todifferent ones of said aircraft, and actuatable to different settingsfor storing the aircraft identication indicia and control data in regardthereto, means for automatically transmitting to said aircraft ightidentification signais and signals comprising a request for a reportfrom the aircraft, said aircraft having receiving apparatus selectivelyresponsive to the flight identification signals and a settable devicefor storing electrical signal conditions comprising a report, means insaid aircraft for transmitting said report comprising means fortransmitting the flight identification signals and means controlled bythe settings of the aircraft signal storage device for transmittingsignals comprising the report data stored therein, and means associatedwith the flight progress posting apparatus and responsive to said reportsignals for resetting selected ones of the first named signal storagedevices in accordance with the data in the received report.

18. A system for posting information regarding the movements ofaircraft, comprising an assembly of flight progress posting apparatusembodying a plurality of groups of signal storage devices, assignable todifferent ones of said aircraft, and actuatable to different settingsfor storing the aircraft identification indicia and control dataincluding the estimated times at which the aircraft Will have reached aparticular zone along the flight path, means for automaticallytransmitting Fix marker signals across the flight path, means forautomatically transmitting to

